CN115335275B

CN115335275B - Steering control device, steering control method, and storage device

Info

Publication number: CN115335275B
Application number: CN202180024050.1A
Authority: CN
Inventors: 青木崇
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2020-03-25
Filing date: 2021-01-25
Publication date: 2024-03-01
Anticipated expiration: 2041-01-25
Also published as: US20230017841A1; CN115335275A; WO2021192572A1; JP2021154783A; JP7156329B2

Abstract

A steering control device (1) for controlling steering of a vehicle (2) by a steering actuator (3) is provided with: a track following control unit (110) that adjusts a target angle (theta t) of a steering angle (theta) given to a steering tire of a vehicle (2) by track following control that causes a self-state quantity (Z) including the position of the vehicle to follow a target track (Tz); and an angle follow-up control unit (120) that adjusts a command value (Oa) that is given to the steering actuator (3) and that corresponds to the actual angle (thetar) by angle follow-up control that causes the actual angle (thetar) of the steering angle (thetar) to follow the target angle (thetat). The track following control unit (110) forces the target angle (thetat) to a fixed angle (thetaf) during a stop control period (delta s) that accompanies the stop of the vehicle (2).

Description

Steering control device, steering control method, and storage device

Cross Reference to Related Applications

The present application is based on patent application No. 2020-54729 of japanese application at 25/3/2020, the content of which is incorporated by reference in its entirety.

Technical Field

The present disclosure relates to a steering control technique that controls steering of a vehicle based on a steering actuator.

Background

As a steering control technique, patent document 1 discloses the following technique: on the condition of the stop detection of the vehicle, the steering angle of the vehicle is reduced by the power steering motor to approach 0 degrees in the straight line.

Patent document 1: japanese patent laid-open publication 2016-215897

However, in the technique disclosed in patent document 1, when the steering angle is shifted from 0 degrees at the next start of the vehicle while the vehicle is stopped, an uncomfortable feeling is given to the occupant. Therefore, if the power steering motor is controlled to maintain the steering angle while the vehicle is stopped, a new problem arises.

This problem is a phenomenon in which the command value given to the power steering motor to hold and control the steering angle fluctuates due to disturbance, and thus the steering angle also fluctuates. This is because, in a configuration in which steering angle adjustment in a power steering motor is controlled along a target path determined based on positional information of a vehicle as in the technique disclosed in patent document 1, input information from a sensor system giving the positional information affects as disturbance. Such a fluctuation in the steering angle of the vehicle during the stop also gives an uncomfortable feeling to the occupant, and thus improvement is desired.

Disclosure of Invention

The present disclosure addresses the problem of providing a steering control device that suppresses the sense of discomfort of an occupant in a vehicle while the vehicle is stationary. Another object of the present disclosure is to provide a steering control method that suppresses an uncomfortable feeling of an occupant in a vehicle while the vehicle is parked. Another object of the present disclosure is to provide a steering control program that suppresses an uncomfortable feeling of a passenger in a vehicle while the vehicle is stationary.

The following describes the embodiments of the present disclosure for solving the problems.

A first aspect of the present disclosure is a steering control device that controls steering of a vehicle by a steering actuator, including:

a track following control unit that adjusts a target angle of a steering angle given to a tire of the vehicle by track following control that causes a state quantity of the vehicle to follow a target track; and

an angle follow-up control unit that adjusts a command value that is given to the steering actuator and corresponds to the actual angle by angle follow-up control that causes the actual angle of the steering angle to follow the target angle,

the track following control unit forces the target angle to a fixed angle during stop control accompanying the stop of the vehicle.

A second aspect of the present disclosure is a steering control method of controlling steering of a vehicle based on a steering actuator, including:

A track following control step of adjusting a target angle of a steering angle given to a tire of the vehicle by track following control for causing a self-state quantity including a position of the vehicle to follow a target track; and

an angle follow-up control step of adjusting a command value which is given to the steering actuator and corresponds to the actual angle by an angle follow-up control for causing the actual angle of the steering angle to follow the target angle,

the track following control step forces the target angle to a fixed angle during stop control accompanying the stop of the vehicle.

A third mode of the present disclosure is a steering control program containing a command that causes a processor to execute in order to control steering of a vehicle based on a steering actuator,

the commands include:

the track following control step forces the target angle to a fixed angle during a stop control period accompanying a stop of the vehicle.

In these first to third aspects, the command value given to the steering actuator is adjusted by the angle follow-up control that causes the actual angle of the steering angle to follow the target angle of the steering angle given to the tire of the vehicle. Therefore, the target angle used for the angle follow-up control is adjusted by the track follow-up control for making the own state quantity including the position of the vehicle follow the target track. However, during the stop control accompanying the stop of the vehicle, the target angle is forced to be a fixed angle. Accordingly, the actual angle corresponding to the command value, which follows the target angle of the fixed angle, is given to the tire from the steering actuator, and the variation in the steering angle, which is the actual angle, can be restricted. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle of the vehicle while it is stopped can be suppressed.

A fourth aspect of the present disclosure is a steering control device that controls steering of a vehicle by a steering actuator, including:

the angle follow-up control unit forces the command value to a fixed value during a stop control period accompanying a stop of the vehicle.

A fifth aspect of the present disclosure is a steering control method of controlling steering of a vehicle based on a steering actuator, including:

the angle follow-up control step forces the command value to a fixed value during a stop control period accompanying a stop of the vehicle.

A sixth aspect of the present disclosure is a steering control program including a command that causes a processor to execute in order to control steering of a vehicle based on a steering actuator,

The commands include:

In these fourth to sixth aspects, the target angle of the steering angle given to the tire of the vehicle is adjusted by track following control for causing the own state quantity including the position of the vehicle to follow the target track. Therefore, the command value given to the steering actuator is adjusted by the angle follow-up control that causes the actual angle of the steering angle to follow the adjustment target angle in the track follow-up control. However, during the stop control accompanying the stop of the vehicle, the command value is forced to a fixed value. Accordingly, the actual angle corresponding to the command value of the fixed value is given to the tire from the steering actuator, and the variation of the steering angle, which is the actual angle, can be restricted. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle of the vehicle while it is stopped can be suppressed.

Drawings

Fig. 1 is a block diagram showing the overall structure of a steering control apparatus according to a first embodiment.

Fig. 2 is a block diagram showing a detailed structure of the steering control apparatus according to the first embodiment.

Fig. 3 is a schematic diagram for explaining the control switching unit according to the first embodiment.

Fig. 4 is a schematic diagram for explaining the control switching unit according to the first embodiment.

Fig. 5 is a schematic diagram for explaining the control switching unit according to the first embodiment.

Fig. 6 is a block diagram for explaining the track following control unit according to the first embodiment.

Fig. 7 is a diagram for explaining the track following control unit according to the first embodiment.

Fig. 8 is a block diagram for explaining the angle follow-up control unit according to the first embodiment.

Fig. 9 is a flowchart showing a steering control method according to the first embodiment.

Fig. 10 is a flowchart showing a steering control method according to the first embodiment.

Fig. 11 is a block diagram showing a detailed structure of a steering control apparatus according to the second embodiment.

Fig. 12 is a diagram for explaining the track following control unit according to the second embodiment.

Fig. 13 is a diagram for explaining the track following control unit according to the second embodiment.

Fig. 14 is a block diagram for explaining the track following control unit according to the second embodiment.

Fig. 15 is a flowchart showing a steering control method according to the second embodiment.

Fig. 16 is a block diagram showing a detailed structure of the steering control apparatus according to the third embodiment.

Fig. 17 is a graph for explaining the angle follow-up control unit according to the third embodiment.

Fig. 18 is a block diagram for explaining the angle follow-up control unit according to the third embodiment.

Fig. 19 is a flowchart showing a steering control method according to the third embodiment.

Fig. 20 is a block diagram showing a detailed structure of a steering control apparatus according to the fourth embodiment.

Fig. 21 is a diagram for explaining the angle follow-up control unit according to the fourth embodiment.

Fig. 22 is a diagram for explaining the angle follow-up control unit according to the fourth embodiment.

Fig. 23 is a block diagram for explaining the angle follow-up control unit according to the fourth embodiment.

Fig. 24 is a flowchart showing a steering control method according to the fourth embodiment.

Detailed Description

Hereinafter, a plurality of embodiments will be described with reference to the drawings. In addition, the same reference numerals are given to the components corresponding to those in each embodiment, and a repetitive description thereof may be omitted. In the case where only a part of the structure is described in each embodiment, the structure of the other embodiment described above can be applied to other parts of the structure. In addition, not only the combination of the structures described in the descriptions of the embodiments, but also the structures of the embodiments may be partially combined with each other unless the description is given, unless the combination is particularly troublesome.

(first embodiment)

As shown in fig. 1, a steering control device 1 according to a first embodiment is mounted on a vehicle 2. The vehicle 2 is, for example, a high-speed drive assist vehicle, an automated driving vehicle, or the like, which can stably or temporarily perform automated steering control by the steering control device 1. In the vehicle 2, a steering angle θ of a tire (hereinafter referred to as a steering tire) 20 of at least one pair of steering wheels with respect to the front-rear direction is adjusted at any time in accordance with automatic steering control by the steering control device 1. The vehicle 2 is mounted with a steering actuator 3, a sensor system 4, and a drive control device 5 together with the steering control device 1.

As shown in fig. 2, the steering actuator 3 includes an electric steering motor 30 and a speed reducer, not shown. The steering actuator 3 may also constitute a power steering system mechanically cooperating with a steering wheel (not shown) of the vehicle 2. The steering actuator 3 may also constitute a steer-by-wire system that is mechanically disconnected from and electrically cooperates with the steering wheel of the vehicle 2.

The steering actuator 3 amplifies the torque generated by the steering motor 30 by a speed reducer and outputs the amplified torque in accordance with the command value Oa from the steering control device 1. The torque is transmitted from the steering actuator 3 to the steering tire 20, so that the steering angle θ of the tire 20 shown in fig. 1 changes. Here, for the steering angle θ, a positive (+) value is given on the right side and a negative (-) value is given on the left side with respect to the front-rear direction of the vehicle 2. Similarly, positive and negative values are given to the command value Oa to the steering actuator 3 and the output value Ao from the steering actuator 3.

As shown in fig. 1 and 2, the sensor system 4 includes an outside sensor 40 and an inside sensor 41. The outside world sensor 40 acquires information of the outside world that becomes the surrounding environment of the vehicle 2. The outside world sensor 40 may also acquire outside world information by detecting an object existing outside the vehicle 2. The object detection type external sensor 40 is, for example, at least one of a camera, liDAR (Light Detection and Ranging/Laser Imaging Detection and Ranging: light detection and ranging/laser imaging detection and ranging), radar, sonar, and the like. The outside world sensor 40 may also acquire outside world information by receiving a specific signal from a satellite of a GNSS (Global Navigation Satellite System: global navigation satellite system) or a roadside machine of an ITS (Intelligent Transport Systems: intelligent transportation system) existing outside the vehicle 2. The external sensor 40 of the signal receiving type is, for example, at least one of a GNSS receiver and a telematics receiver.

The inner limit sensor 41 acquires information of an inner limit that becomes an internal environment of the vehicle 2. The inner sensor 41 may acquire inner information by detecting a specific physical quantity of motion in the inner of the vehicle 2. The physical quantity detection type inner limit sensor 41 is, for example, at least two of a steering angle sensor 42, a travel speed sensor 44, a steering output sensor, an inertial sensor, and the like, including the steering angle sensor 42 and the travel speed sensor 44. The steering angle sensor 42 acquires an actual angle θr that is an actual steering angle θ of the steering tire 20. The running speed sensor 44 acquires the running speed V of the vehicle 2.

The driving control device 5 is connected to the sensor system 4 via at least one of a LAN (Local Area Network: local area network), wiring, an internal bus, and the like, for example. The driving control device 5 is an ECU (Electronic Control Unit: electronic control unit) dedicated for, for example, high-speed driving assistance or dedicated for automatic driving control, which is a control that is higher than the steering control device 1 and can stably or temporarily automatically control the driving of the entire vehicle 2. Here, the temporary automatic control may be realized by being able to switch between the automatic driving mode and the manual driving mode for the vehicle 2.

The driving control device 5 performs control judgment that is higher than the steering control device 1 by various pieces of acquired information based on the outside sensor 40 and the inside sensor 41. Therefore, in the automatic control, the driving control device 5 generates a control flag indicating a control instruction requested to the steering control device 1. The control flags include a static steering flag Fs. The static steering flag Fs is a flag for instructing the steering control device 1 with static steering control for switching the steering angle θ of the steering tire 20 to the necessary angle at the time of the next start in stopping the vehicle 2.

The steering control device 1 is connected to the steering actuator 3, the sensor system 4, and the steering control device 5 via at least one of LAN (Local Area Network), wiring, an internal bus, and the like, for example. The steering control apparatus 1 is configured to include at least one dedicated computer. The dedicated computer constituting the steering control device 1 may be an ECU dedicated for steering that controls the steering actuator 3. The dedicated computer constituting the steering control apparatus 1 may be an ECU of a positioner used for high-speed driving assistance or automatic driving control of the vehicle 2. The dedicated computer constituting the steering control device 1 may be an ECU of a navigation device that navigates the driving of the vehicle 2. The same ECU as the drive control device 5 may also serve as the steering control device 1.

The special purpose computer constituting the steering control apparatus 1 includes at least one memory 10 and a processor 12. The memory 10 is at least one non-transitory physical storage medium (non-transitory tangible storage medium) such as a semiconductor memory, a magnetic medium, and an optical medium that non-temporarily stores a program and data readable by a computer. The processor 12 includes, for example, at least one of a CPU (Central Processing Unit: central processing unit), a GPU (Graphics Processing Unit: graphics processor), a RISC (Reduced Instruction Set Computer: reduced instruction set computer) -CPU, and the like as a core.

The processor 12 executes a plurality of commands included in a steering control program stored in the memory 10. As a result, the steering control device 1 constructs a plurality of functional units for controlling the steering of the vehicle 2 as shown in fig. 2. In this way, in the steering control device 1, the estimation program stored in the memory 10 for controlling the steering of the vehicle 2 causes the processor 12 to execute a plurality of commands, thereby constructing a plurality of functional units. The plurality of functional units include a control switching unit 100, a track following control unit 110, and an angle following control unit 120.

The control switching unit 100 switches between a stop control period Δs during which the stop control is executed in association with the stop of the vehicle 2 and a normal control period Δn during which normal control is executed outside the stop control period Δs. Therefore, the control switching unit 100 monitors the start condition for starting the stop control period Δs. As shown in fig. 3, the start conditions of the stop control period Δs include a speed condition Cs1 and a steering condition Cs2. Therefore, the control switching unit 100 maintains the normal control period Δn during a period in which at least one of the speed condition Cs1 and the steering condition Cs2 is not satisfied. On the other hand, if both the speed condition Cs1 and the steering condition Cs2 are satisfied, the control switching unit 100 starts the stop control period Δs.

The satisfaction of the speed condition Cs1 is that the running speed V acquired by the running speed sensor 44 falls within the allowable speed range. The allowable speed range may be set to a value range equal to or smaller than the threshold value, with the upper limit value of the running speed V at which stop control is allowed as the threshold value. The allowable speed range may be set to a value range smaller than a threshold value by using a lower limit value of the travel speed V for which stop control is prohibited as the threshold value.

The satisfaction of the steering condition Cs2 is that the angular velocity related to the actual angle θr acquired by the steering angle sensor 42 falls within the allowable angular velocity range. The allowable angular velocity range may be set to a numerical value range equal to or smaller than a threshold value, which is an upper limit value of the angular velocity at which the control is allowed to stop. The allowable angular velocity range may be set to a value range smaller than a threshold value, with the lower limit value of the angular velocity at which stop control is prohibited as the threshold value.

The control switching unit 100 monitors a release condition for releasing the time Δs after the start of the stop control period Δs. As shown in fig. 4, the release conditions of Δs during the stop control include a speed condition Cr1, a static steering condition Cr2, and a track condition Cr3. Therefore, the control switching unit 100 maintains the stop control period Δs during the period when all of the speed condition Cr1, the static steering condition Cr2, and the track condition Cr3 are not satisfied. On the other hand, if at least one of the speed condition Cr1, the static steering condition Cr2, and the track condition Cr3 is satisfied, the control switching unit 100 releases the stop control period Δs.

The satisfaction of the speed condition Cr1 is that the running speed V acquired by the running speed sensor 44 rises to be within the release speed range. The release speed range may be set to a value range equal to or greater than a threshold value, which is a lower limit value of the travel speed V for releasing the stop control. The release speed range may be set to a value range exceeding a threshold value by using an upper limit value of the running speed V for which stop control is maintained as the threshold value.

The condition for the establishment of the static steering condition Cr2 is that a static steering flag Fs is given from the drive control device 5. That is, the static steering condition Cr2 is established along with the static steering of the steering tire 20 during the stop control period Δs.

The condition for establishment of the track condition Cr3 is to assume a track shift as shown in fig. 5 in the stop control period Δs. The track deviation is defined by a track deviation δt between an estimated track Te corresponding to the actual angle θr acquired by the steering angle sensor 42 and a target track Tz acquired by the track following control unit 110, which will be described later. Here, the estimated track Te is obtained by performing travel estimation at the turning radius indicated by the ratio of the Wheelbase (Wheelbase) and the actual angle θr in the vehicle 2. Therefore, when the integrated value related to the track deviation δt between the estimated track Te and the target track Tz (hereinafter referred to as the track difference integrated value) increases within the cancellation offset range, it is determined that the track offset is the one in which the assumed track condition Cr3 is satisfied. Here, the misalignment removal range may be set to a numerical range equal to or greater than a threshold value, which is a lower limit value of the track difference integrated value for canceling the stop control. The misalignment removal range may be set to a value range exceeding a threshold value, which is an upper limit value of the track difference integrated value that maintains the stop control.

The control switching unit 100 gives a stop control start flag Fon to the track following control unit 110 and the angle following control unit 120 from the start timing to the release timing of the stop control period Δs. On the other hand, the control switching unit 100 gives a stop control closing flag Foff to the track following control unit 110 and the angle following control unit 120 from the start timing to the release timing of the normal control period Δn.

The track following control unit 110 shown in fig. 2 controls the travel track followed by the vehicle 2. Therefore, the track following control unit 110 includes a state quantity acquisition unit 111, a target track acquisition unit 112, a target angle adjustment unit 113, and a forced control unit 114 as sub-functional units of different functions.

The state quantity acquisition unit 111 acquires the state quantity Z of the vehicle 2 by estimation processing based on various acquired information of the external sensor 40 and the internal sensor 41. The own state quantity Z includes the own position of the vehicle 2 and the yaw angle. The self-state quantity Z may further include at least one of a running speed V, an acceleration, and the like, for example.

The target track acquisition unit 112 acquires the target track Tz as a travel track of the vehicle 2 in which the time-series change of the self state quantity Z is specified. The target track Tz is generated based on a control instruction indicated by a control flag given from the drive control device 5.

The target angle adjustment unit 113 executes track following control for causing the self-state quantity Z acquired by the state quantity acquisition unit 111 to follow the target track Tz acquired by the target track acquisition unit 112. By the track following control, the target angle adjustment unit 113 adjusts the target angle θt of the steering angle θ given to the angle following control unit 120 so that the state quantity Z thereof approaches the target track Tz by a predetermined amount. Therefore, the target angle adjustment unit 113 generates the target angle θt as shown in fig. 6 by adding the feedforward angle θc based on the feedforward control to the feedback angle θb based on the feedback control. That is, the track following control by the target angle adjustment unit 113 is realized by a combination of feedback control and feedforward control.

In the feedback control, the target angle adjustment unit 113 obtains the lateral deviation δp and the yaw angle deviation δy by the deviation calculation. The lateral deviation δp is a deviation between the lateral position of the vehicle 2 in the self-state quantity Z and a predetermined position based on the target track Tz. The yaw angle deviation δy is a deviation between the yaw angle of the vehicle 2 in the self-state quantity Z and a predetermined angle based on the target trajectory Tz.

In the feedback control, the target angle adjustment section 113 converts the integrated operation value of the lateral deviation δp into an independent control angle θi based on the integral gain. However, the integral value of the lateral deviation δp is locked to a fixed value during the stop control period Δs in which the stop control on flag Fon is given from the control switching unit 100. In the feedback control, the target angle adjustment unit 113 converts the lateral deviation δp and the yaw angle deviation δy into independent control angles θp and θy based on the lateral deviation gain and the yaw angle deviation gain, respectively. In the feedback control, the target angle adjustment unit 113 generates the feedback angle θb by adding the converted independent control angles θi, θp, and θy to each other.

In the feedforward control, the target angle adjustment section 113 converts the curvature Tzc of the target track Tz into a feedforward angle θc based on the conversion gain. The target angle adjustment unit 113 determines the target angle θt by adding the converted feedforward angle θc and the converted feedback angle θb.

The forcing control unit 114 shown in fig. 2 and 6 forces the target angle θt given to the angle follow-up control unit 120 by the target angle adjustment unit 113 to the fixed angle θf shown in fig. 7 during the stop control period Δs in which the stop control on flag Fon is given from the control switching unit 100. That is, the forced control unit 114 executes the stop control for the stop control period Δs. The forcing control unit 114 of the first embodiment sets the fixed angle θf to the same angle as the target angle θt at the start timing from the start timing to the release timing of the stop control period Δs. Thus, the target angle θt given to the angle follow-up control unit 120 is continuously maintained at the fixed angle θf throughout the stop control period Δs, regardless of the track follow-up control in the target angle adjustment unit 113. Further, fig. 7 is shown only with respect to the positive side in the target angle θt.

As shown in fig. 6, the forced control unit 114 may hold the target angle θt itself at the fixed angle θf as a control variable of the control point P1t after addition in the target angle adjustment unit 113. Alternatively, the forced control unit 114 may fix a predetermined control variable to each of the feedback control and the feedforward control in the target angle adjustment unit 113, thereby maintaining the target angle θt at a fixed angle θf.

Here, any one of the control points P2b, P3b, P4b is selected for a variable fixed point at which the control variable is fixed in the feedback control. When the control point P2b is selected as the variable fixed point, the feedback angle θb as the control variable is fixed. When the control point P3b is selected as the variable fixed point, the lateral deviation δp and the yaw angle deviation δy as the control variables are fixed. When the control point P4b is selected as the variable fixed point, the self position and yaw angle in the self state quantity Z as the control variable and the predetermined amount related to the self position and yaw angle in the target trajectory Tz as the control variable are fixed.

On the other hand, either one of the control points P2f, P3f is selected for a variable fixed point at which the control variable is fixed in the feedforward control. When the control point P2f is selected as the variable fixed point, the feedforward angle θc as the control variable is fixed. When the control point P2f is selected as the variable fixed point, the curvature Tzc of the target track Tz as the control variable is fixed.

The forced control unit 114 releases the stop control for forcing the target angle θt to the fixed angle θf during the normal control period Δn in which the stop control off flag Foff is given from the control switching unit 100, and then executes the normal control as shown in fig. 7. Thus, during the normal control period Δn, the target angle θt that is normally adjusted by the track following control by the target angle adjustment unit 113 is directly given to the angle following control unit 120.

Here, the forced control unit 114 executes the release control by changing the stop control on flag Fon from the control switching unit 100 to the stop control off flag Foff, that is, by switching to the normal control period Δn in response to the release of the stop control period Δs. In the release control, the forcing control unit 114 gradually changes the target angle θt given from the target angle adjustment unit 113 to the angle follow-up control unit 120 from the fixed angle θf of the stop control period Δs to the adjustment angle normally adjusted by the track follow-up control of the target angle adjustment unit 113 as shown in fig. 7. At this time, the gradual change of the target angle θt is achieved by changing the control variable at the control point corresponding to the stop control among the control points P1t, P2b, P3b, P4b, P2f, P3 f. When the release control is completed by completion of the gradual change, the target angle θt is normally adjusted by the track following control of the target angle adjustment unit 113.

The angle follow-up control unit 120 shown in fig. 2 controls the steering angle θ that the vehicle 2 follows. Accordingly, the angle follow-up control unit 120 executes angle follow-up control for causing the actual angle θr acquired by the steering angle sensor 42 to follow the target angle θt from the target angle adjustment unit 113. By the angle follow-up control, the angle follow-up control portion 120 adjusts the command value Oa given to the steering actuator 3 so that the actual angle θr approaches the target angle θt. Accordingly, the angle follow-up control unit 120 generates the command value Oa by PID control based on the angular deviation δθ between the target angle θt and the actual angle θr, as shown in fig. 8. That is, the angular tracking control by the angular tracking control unit 120 is realized by PID control.

Here, the angle follow-up control section 120 performs a restriction operation such that the output value Ao of the steering actuator 3 is restricted by the last value holding of the instruction value Oa before the instruction value Oa based on the PID control is given to the steering actuator 3. At this time, the limit value of the output value Ao is set to a value corresponding to the rated output of the steering motor 30, for example.

The steering actuator 3 adjusts the output value Ao shown in fig. 1 and 2 according to the command value Oa adjusted by the angle follow-up control unit 120. As a result, by controlling the steering angle θ of the steering tire 20 toward the target angle θt, the actual angle θr of the steering angle θ corresponds to the command value Oa given to the steering actuator 3.

By the control switching unit 100, the track following control unit 110, and the angle following control unit 120 being common to the above, a flow of a steering control method (hereinafter referred to as a steering control flow) in which the steering control device 1 controls steering of the vehicle 2 will be described below with reference to fig. 9 and 10. In the steering control flow, "S" means a plurality of steps executed by a plurality of commands included in the steering control program, respectively.

The control switching flow shown in fig. 9 in the steering control flow is repeatedly executed. In S101 of the control switching flow, the control switching unit 100 determines whether or not both the speed condition Cs1 and the steering condition Cs2 are satisfied as the start condition of the stop control period Δs. As a result, when at least one of the speed condition Cs1 and the steering condition Cs2 is not established and a negative determination is made, the present execution of the control switching flow is ended. On the other hand, in the case where an affirmative determination is made, the control switching flow moves to S102.

In S102, the control switching unit 100 fixes the control flag given to the track following control unit 110 and the angle following control unit 120 to the stop control on flag Fon. In the next step S103, the control switching unit 100 determines whether or not at least one of the speed condition Cr1, the static steering condition Cr2, and the track condition Cr3 is satisfied as a release condition for the stop control period Δs. As a result, S103 is repeatedly executed while all of the speed condition Cr1, the static steering condition Cr2, and the track condition Cr3 are not established and a negative determination is made. On the other hand, in the case where an affirmative determination is made, the control switching flow moves to S104.

In S104, the control switching unit 100 fixes the control flag given to the track following control unit 110 and the angle following control unit 120 to the stop control off flag Foff. This ends the current execution of the control switching flow.

The forced control flow shown in fig. 10 of the steering control flow is repeatedly executed in parallel with the control switching flow. In S201 of the forced control, the forced control unit 114 determines whether or not the control flag given from the control switching unit 100 is the stop control on flag Fon. As a result, when the control flag makes a negative determination for stopping the control off flag Foff, the forced control flow advances to S202.

In S202, the target angle adjustment unit 113 adjusts the target angle θt given to the steering angle θ of the angle follow-up control unit 120 by executing the track follow-up control for making the own state quantity Z of the vehicle 2 follow the target track Tz. In next S203, the angle follow-up control unit 120 executes angle follow-up control for causing the actual angle θr of the steering angle θ to follow the target angle θt adjusted in S202, thereby adjusting the command value Oa that is given to the steering actuator 3 and corresponds to the actual angle θr. This completes the execution of the forced control flow.

In the case where an affirmative determination is made in S201, the forced control flow moves to S204. In S204, the forcing control unit 114 forces the target angle θt given from the target angle adjustment unit 113 to the angle follow-up control unit 120 to be maintained at the fixed angle θf regardless of the track follow-up control in the target angle adjustment unit 113. In next S205, the angle follow-up control unit 120 fixes the command value Oa given to the steering actuator 3 by performing angle follow-up control for making the actual angle θr follow the target angle θt forcibly held in S204. The command value Oa at this time can be considered as a fixed value Of.

Further, in the next S206, the forced control section 114 determines whether or not the control flag given from the control switching section 100 is the stop control off flag Foff. As a result, when the control flag makes a negative determination for the stop control on flag Fon, the process returns to S204. In this way, during the negative determination at S206, that is, during the stop control period Δs, S204 to S206 are repeatedly executed, and the target angle θt and the command value Oa are maintained at the fixed angle θf and the fixed value Of, respectively.

In the case where an affirmative determination is made in S206, the forced control flow moves to S207. In S207, the forcing control unit 114 executes release control. At this time, the forcing control unit 114 changes the target angle θt given to the angle follow-up control unit 120 from the fixed angle θf side at the transition timing to S207 (i.e., the release timing of the stop control period Δs) to the adjustment angle side of the track follow-up control by the target angle adjustment unit 113. In next S208, the angle follow-up control unit 120 executes angle follow-up control for causing the actual angle θr to follow the target angle θt changed in S207, thereby changing the command value Oa given to the steering actuator 3.

Further, in the following 209, the forced control unit 114 determines whether or not the target angle θt in the change from the fixed angle θf is restored to the adjustment angle based on the track following control by the target angle adjustment unit 113 within the positive and negative error range. As a result, if a negative determination is made, the process returns to S207. In this way, during the period of negative determination in S209, S207 to S209 are repeatedly executed, and the target angle θt and the command value Oa gradually change. On the other hand, if an affirmative determination is made in S209, the current execution of the forced control flow is ended.

In the first embodiment described so far, S201, S202, S204, S206, S207, S209 correspond to the "track following control process", and S203, S205, S208 correspond to the "angle following control process".

(effects of action)

The operational effects of the first embodiment described above will be described below.

In the first embodiment, the command value Oa given to the steering actuator 3 is adjusted by the angle following control of making the actual angle θr of the steering angle θ follow the target angle θt of the steering angle θ given to the steering tire 20 of the vehicle 2. Therefore, the target angle θt used in the angle follow-up control is adjusted by the track follow-up control for causing the own state quantity Z including the position of the vehicle 2 to follow the target track Tz. However, during the stop control period Δs accompanying the stop of the vehicle 2, the target angle θt is forced to be the fixed angle θf. Accordingly, the actual angle θr corresponding to the command value Oa, which follows the fixed angle θf, is given from the steering actuator 3 to the steering tire 20, and the variation of the steering angle θ, which is the actual angle θr, can be restricted. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while it is stopped can be suppressed. The sense of incongruity that can be suppressed here is, for example, a sense of incongruity felt by at least one of the steering tire 20 by the occupant, abnormal noise or vibration generated thereby, rotation of the steering wheel when present in the vehicle 2, and the like.

According to the first embodiment, the target angle θt is maintained at the fixed angle θf throughout the stop control period Δs. Accordingly, the actual angle θr corresponding to the command value Oa, which follows the fixed angle θf, is given from the steering actuator 3 to the steering tire 20, and the variation of the steering angle θ, which is the actual angle θr, can be restricted throughout the stop control period Δs. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while it is stopped can be continuously suppressed.

According to the first embodiment, the stop control period Δs is released in association with the static steering of the steering tire 20 during the stop control period Δs. Accordingly, when static steering in which the steering angle θr, which is the actual angle θr that follows the target angle θt and corresponds to the command value Oa, is supposed to vary, normal adjustment of the target angle θt based on the track following control can be permitted. Therefore, the occupant can suppress not only the sense of incongruity caused by the variation in the steering angle θ in the vehicle 2 while it is stopped, but also the sense of incongruity caused by the limitation of the variation.

According to the first embodiment, in the case where the stop control period Δs assumes a track shift between the estimated track Te corresponding to the actual angle θr and the target track Tz, the stop control period Δs is released. Accordingly, for the track shift in which the change is assumed at the steering angle θ, which is the actual angle θr that follows the target angle θt and corresponds to the command value Oa, normal adjustment of the target angle θt based on the track following control can be permitted. Therefore, the occupant can suppress not only the sense of incongruity caused by the variation in the steering angle θ in the vehicle 2 while it is stopped, but also the sense of incongruity caused by the limitation of the variation.

According to the first embodiment, the target angle θt gradually changes from the fixed angle θf toward the adjustment angle by the track following control with the release of the stop control period Δs. Accordingly, when the steering angle θ is returned from the fixed angle θf of Δs during the stop control to the adjustment angle that is normally adjusted by the track following control, the abrupt change in the steering angle θ can be avoided. Therefore, the occupant can suppress not only the sense of incongruity caused by the fluctuation of the steering angle θ in the vehicle 2 while it is stopped, but also the sense of incongruity caused by the restriction release of the fluctuation.

(second embodiment)

As shown in fig. 11 to 15, the second embodiment is a modification of the first embodiment. The track following control unit 2110 according to the second embodiment shown in fig. 11 differs from the first embodiment in that the forced control unit 2114 is in stop control during a stop control period Δs.

In the stop control, the forcing control unit 2114 defines the dead zone dθ as shown in fig. 12 for the stop control period Δs for which the stop control on flag Fon is given from the control switching unit 100. Therefore, the forcing control unit 2114 sets the dead zone dθ of the stop control period Δs on both positive and negative sides as the range of the angle assumed to be the fixed angle θf among the target angles θt adjusted by the track following control of the target angle adjustment unit 113. As shown in fig. 12 and 13, in the forced control unit 2114 of the second embodiment, in particular, the dead zone dθ is set to be within an angle range having a larger width on each of the positive and negative sides as the running speed V acquired by the running speed sensor 44 decreases during the stop control period Δs. Fig. 12 and 13 are shown only on the positive side of the target angle θt.

In the stop control, for example, when the adjustment angle by the track following control by the target angle adjustment unit 113 is out of the dead zone dθ due to the high traveling speed V, the forced control unit 2114 readjusts the target angle θt given to the angle following control unit 120 to a difference calculation value between the adjustment angle and the width of the dead zone dθ. At this time, the forcing control unit 2114 supplies the width of the dead zone dθ on the same side to the difference operation for the positive and negative of the adjustment angle based on the track following control. On the other hand, in the stop control, for example, when the adjustment angle by the track following control by the target angle adjustment unit 113 is within the dead zone dθ due to a decrease in the running speed V or the like, the forced control unit 2114 converts the target angle θt given to the angle following control unit 120 into the fixed angle θf. That is, the forcing control unit 2114 forces all the target angles θt in the dead zone dθ among the adjustment angles based on the track following control to the fixed angle θf. By switching between these readjustment processing and forcing processing, the inside-outside abrupt change of the target angle θt given to the angle follow-up control unit 120 in the dead zone dθ is suppressed.

As shown in fig. 14, the forced control unit 2114 may convert the target angle θt itself in the dead zone dθ into a fixed angle θf as a control variable of the control point P1t after addition in the target angle adjustment unit 113. Alternatively, the forcing control unit 2114 may convert the target angle θt in the dead zone dθ into the fixed angle θf by fixing a predetermined control variable in a predetermined range corresponding to the dead zone dθ in each of the feedback control and the feedforward control in the target angle adjustment unit 113. Here, any one of the control points P2b, P3b, P4b similar to the case of the first embodiment is selected for the variable fixed point in the feedback control. On the other hand, one of the control points P2f and P3f similar to the case of the first embodiment is selected for the variable fixed point in the feedforward control.

In addition, the forcing control unit 2114 executes the release control and then executes the normal control in the same manner as in the first embodiment, during the normal control period Δn in which the stop control off flag Foff is given from the control switching unit 100.

The control switching flow in the steering control flow in such a second embodiment is executed based on the first embodiment. On the other hand, the forced control flow in the steering control flow in the second embodiment is different from the first embodiment as shown in fig. 15.

S201 to S203 of the forced control flow are executed with reference to the first embodiment. In S2201 shifted by the affirmative determination of S201, the forcing control unit 2114 determines whether or not the target angle θt based on the track following control in the target angle adjustment unit 113 is within the dead zone dθ corresponding to the travel speed V.

In the case where a negative determination is made in S2201, the forced control flow moves to S2202. In S2202, the forcing control unit 2114 readjust the target angle θt, which is adjusted to be outside the dead zone dθ by the track following control of the target angle adjustment unit 113, to a differential value with the dead zone dθ, which is given to the angle following control unit 120. In next S2203, the angle follow-up control unit 120 adjusts the command value Oa given to the steering actuator 3 by performing angle follow-up control for causing the actual angle θr to follow the target angle θt readjusted in S2202.

In the case where an affirmative determination is made in S2201, the forced control flow moves to S2204. In S2204, the forcing control unit 2114 forcibly converts the target angle θt adjusted to be within the dead zone dθ by the orbit following control of the target angle adjustment unit 113 into the fixed angle θf given to the angle following control unit 120. In next S2205, the angle follow-up control unit 120 fixes the command value Oa given to the steering actuator 3 by performing angle follow-up control that causes the actual angle θr to follow the target angle θt forcibly converted in S204. The command value Oa at this time can be considered as a fixed value Of.

After executing either of S2203, S2205, the forced control flow also moves to S206 with reference to the first embodiment. As a result, when a negative determination is made, the process returns to S2201. On the other hand, in the case where an affirmative determination is made, S207 to S209 are performed with reference to the first embodiment.

In the second embodiment described so far, S201, S202, S2201, S2202, S2204, S206, S207, S209 correspond to the "track following control process", and S203, S2203, S2205, S208 correspond to the "angle following control process".

(effects of action)

The operational effects of the second embodiment described above, which are different from those of the first embodiment, will be described below.

According to the second embodiment, the target angle θt is converted into the fixed angle θf within the dead zone dθ set for the stop control period Δs. Accordingly, the actual angle θr corresponding to the command value Oa, which follows the fixed angle θf in the dead zone dθ, is given from the steering actuator 3 to the steering tire 20, and the variation of the steering angle θ, which is the actual angle θr, can be restricted. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while being stopped can be suppressed as much as possible in accordance with the dead zone dθ.

According to the second embodiment, in the dead zone dθ set to a larger angle range as the traveling speed V of the vehicle 2 decreases in the stop control period Δs, the target angle θt is converted to the fixed angle θf. Accordingly, the variation can be suppressed as the running speed V decreases with respect to the steering angle θ which is the actual angle θr that is more likely to be forced to follow the target angle θt of the fixed angle θf as the running speed V decreases with the stop of the vehicle 2. Therefore, the suppression effect corresponding to the dead zone dθ can be exhibited against the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while it is stopped.

(third embodiment)

As shown in fig. 16 to 19, the third embodiment is a modification of the first embodiment. The forced control unit 114 is omitted from the track following control unit 3110 according to the third embodiment shown in fig. 16. Instead, the angle follow-up control unit 3120 of the third embodiment has a command value adjustment unit 3121 and a forced control unit 3122 as sub-functional units of different functions.

The command value adjustment unit 3121 functions substantially the same as the angle follow-up control unit 120 of the first embodiment. That is, the command value adjustment unit 3121 adjusts the command value Oa that is given to the steering actuator 3 and corresponds to the actual angle θr by the angle following control that causes the actual angle θr to follow the target angle θt based on the target angle adjustment unit 113.

The forcing control unit 3122 shown in fig. 16 and 18 forces the command value Oa given to the steering actuator 3 by the command value adjustment unit 3121 to the fixed value Of shown in fig. 17 during the stop control period Δs in which the stop control on flag Fon is given from the control switching unit 100. That is, the forcing control unit 3122 executes the stop control for the stop control period Δs. The forcing control unit 3122 Of the third embodiment singly sets the fixed value Of from the start timing to the release timing Of the stop control period Δs to the same value as the command value Oa Of the start timing. Thereby, the command value Oa given to the steering actuator 3 is continuously maintained at the fixed value Of throughout the stop control period Δs regardless Of the angle follow-up control in the command value adjustment portion 3121. Fig. 17 is only shown on the positive side of the command value Oa.

As shown in fig. 18, the forcing control unit 3122 may hold the command value Oa to a fixed value Of if by fixing a predetermined control variable in the PID control in the command value adjustment unit 3121. Here, either one of the control points P1a, P2a is selected for a variable fixed point in the PID control. When the control point P1a is selected as the variable fixed point, the command value Oa itself is fixed in correspondence with the limit value of the output value Ao by the limit operation as the control variable. When the control point P2a is selected as the variable fixed point, the angular deviation δθ between the target angle θt and the actual angle θr, which are control variables, is fixed.

The forcing control unit 3122 releases the stop control for forcing the command value Oa to the fixed value Of if during the normal control period Δn in which the stop control off flag Foff is given from the control switching unit 100, and thereafter executes the normal control as shown in fig. 17. Thus, during the normal control period Δn, the command value Oa that is normally adjusted based on the angle follow-up control of the command value adjustment unit 3121 is directly given to the steering actuator 3.

Here, the forcing control unit 3122 executes the release control by changing the stop control on flag Fon from the control switching unit 100 to the stop control off flag Foff, that is, by switching to the normal control period Δn in response to the release of the stop control period Δs. In the release control, the forcing control unit 3122 gradually changes the command value Oa given from the command value adjustment unit 3121 to the steering actuator 3 from the fixed value Of Δs during the stop control period Of as shown in fig. 17 toward the adjustment value normally adjusted by the angle follow control Of the command value adjustment unit 3121. At this time, the control variable is changed at the control point corresponding to the stop control among the control points P1a and P2a, so that the gradual change of the command value Oa is realized. When the release control is completed by completion of the gradual change, the command value Oa is normally adjusted by the track following control of the command value adjusting unit 3121.

The control switching flow in the steering control flow in the third embodiment is executed based on the first embodiment. On the other hand, the forced control flow in the steering control flow in the third embodiment is different from the first embodiment as shown in fig. 19.

Specifically, in S3201 of the forced control flow, the forced control section 3122 determines whether or not the control flag given from the control switching section 100 is the stop control on flag Fon. As a result, in the case where the control flag makes a negative determination for stopping the control off flag Foff, the forced control flow moves to S3202.

In S3202, the target angle adjustment unit 113 adjusts the target angle θt given to the steering angle θ of the angle follow-up control unit 3120 by performing track follow-up control for making the own state quantity Z of the vehicle 2 follow the target track Tz. In the following S3203, the command value adjustment unit 3121 adjusts the command value Oa that is given to the steering actuator 3 and corresponds to the actual angle θr by performing angle following control that causes the actual angle θr of the steering angle θ to follow the target angle θt adjusted in S3202. This completes the execution of the forced control flow.

In the case where an affirmative determination is made in S3201, the forced control flow moves to S3204. In S3204, the target angle adjustment unit 113 adjusts the target angle θt given to the angle follow-up control unit 3120 by performing track follow-up control for making the own state quantity Z of the vehicle 2 follow the target track Tz. However, in S3205 that follows, the forcing control unit 3122 forces the command value Oa given from the command value adjusting unit 3121 to the steering actuator 3 to be maintained at the fixed value Of regardless Of the angle following control in the command value adjusting unit 3121 corresponding to the target angle θt adjusted in S3201.

Further, in S3206, the forced control section 3122 determines whether or not the control flag given from the control switching section 100 is the stop control off flag Foff. As a result, if the control flag is the stop control on flag Fon and a negative determination is made, the process returns to S3204. In this way, during the negative determination Of S3206, that is, during the stop control period Δs, S3204 to S3206 are repeatedly executed, and the command value Oa is maintained at the fixed value Of.

In the case where an affirmative determination is made in S3206, the forced control flow moves to S3207. In S3207, the target angle adjustment unit 113 adjusts the target angle θt given to the steering angle θ of the angle follow-up control unit 3120 by performing track follow-up control for causing the self state quantity Z to follow the target track Tz. However, in the following S3208, the forced control section 3122 executes the release control regardless of the target angle θt adjusted in S3201. At this time, the forcing control unit 3122 changes the command value Oa given to the steering actuator 3 from the fixed value Of side Of the transition timing to S3208 (i.e., the release timing Of the stop control period Δs) toward the adjustment value side Of the angle follow-up control by the command value adjustment unit 3121 corresponding to the target angle θt adjusted by S3201.

Further, in the following 3209, the forcing control unit 3122 determines whether or not the command value Oa in the change from the fixed value Of is restored to the adjustment value based on the angle follow-up control Of the command value adjustment unit 3121 within the positive and negative error range. As a result, in the case where a negative determination is made, the flow returns to S3207. In this way, during the period of negative determination at S3209, S3207 to S3209 are repeatedly executed, and the command value Oa gradually changes. On the other hand, if an affirmative determination is made in S3209, the current execution of the forced control flow ends.

In the third embodiment described so far, S3202, S3204, and S3207 correspond to the "track following control process", and S3201, S3203, S3205, S3206, S3208, and S3209 correspond to the "angle following control process".

(effects of action)

The operational effects of the third embodiment described above will be described below.

In the third embodiment, the target angle θt of the steering angle θ given to the steering tire 20 of the vehicle 2 is adjusted by the track following control in which the own state quantity Z including the position of the vehicle 2 follows the target track Tz. Therefore, the command value Oa given to the steering actuator 3 is adjusted by the angle follow-up control for making the actual angle θr of the steering angle θ follow the adjustment target angle θt in the track follow-up control. However, during the stop control period Δs accompanying the stop Of the vehicle 2, the command value Oa is forced to the fixed value Of. Accordingly, the actual angle θr corresponding to the fixed value Of is given from the steering actuator 3 to the steering tire 20, and the variation Of the steering angle θ, which is the actual angle θr, can be restricted. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while it is stopped can be suppressed. The sense of incongruity that can be suppressed here is the same as that described in the operational effects of the first embodiment.

According to the third embodiment, the command value Oa is maintained at the fixed value Of throughout the stop control period Δs. Accordingly, the actual angle θr corresponding to the fixed value Of is given from the steering actuator 3 to the steering tire 20, so that the variation Of the steering angle θ, which becomes the actual angle θr, can be restricted throughout the stop control period Δs. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while it is stopped can be continuously suppressed.

In the third embodiment, the stationary steering of the vehicle 2 is accompanied by the stop control period Δs by the execution of the control switching flow based on the first embodiment, and the stop control period Δs is released. Accordingly, when static steering in which a change is assumed as the steering angle θ of the actual angle θr corresponding to the command value Oa, normal adjustment of the command value Oa based on the angle follow-up control can be permitted. Therefore, the occupant can suppress not only the sense of incongruity caused by the variation in the steering angle θ of the vehicle 2 while it is stopped, but also the sense of incongruity caused by the limitation of the variation.

In the third embodiment, by executing the control switching flow based on the first embodiment, when the stop control period Δs assumes a track shift between the estimated track Te corresponding to the actual angle θr and the target track Tz, the stop control period Δs is released. Accordingly, for the track offset that is supposed to vary at the steering angle θ, which is the actual angle θr corresponding to the command value Oa, normal adjustment of the command value Oa based on the angle follow-up control can be allowed. Therefore, the occupant can suppress not only the sense of incongruity caused by the variation in the steering angle θ of the vehicle 2 while it is stopped, but also the sense of incongruity caused by the limitation of the variation.

According to the third embodiment, the command value Oa gradually changes from the fixed value Of to the adjustment value based on the angle follow-up control with the release Of the stop control period Δs. Accordingly, when the command value Oa is restored from the fixed value Of Δs in the stop control period Of time Of the fixed value Of Δs to the adjustment value Of the normal adjustment by the angle follow-up control, the abrupt change Of the command value Oa can be avoided. Therefore, the occupant can suppress not only the sense of incongruity caused by the fluctuation of the steering angle θ of the vehicle 2 while it is stopped, but also the sense of incongruity caused by the restriction release of the fluctuation.

(fourth embodiment)

As shown in fig. 20 to 24, the fourth embodiment is a modification of the third embodiment. The angle follow-up control unit 4120 according to the fourth embodiment shown in fig. 20 differs from the third embodiment in the stop control of the stop control period Δs by the forced control unit 4122.

In the stop control, the forced control unit 4122 defines the dead zone Do as shown in fig. 21 for the stop control period Δs for which the stop control on flag Fon is given from the control switching unit 100. Therefore, the forcing control unit 4122 sets the dead zone Do Of the stop control period Δs on both positive and negative sides as the range Of the value assumed to be the fixed value Of the command value Oa adjusted by the angle follow-up control Of the command value adjusting unit 3121. As shown in fig. 21 and 22, in the forced control unit 4122 according to the fourth embodiment, in particular, the dead zone Do is set to be within a numerical range having a larger width on each of the positive and negative sides as the running speed V acquired by the running speed sensor 44 decreases during the stop control period Δs. Fig. 21 and 22 show only the positive side of the command value Oa.

In the stop control, for example, when the adjustment value of the angle follow-up control by the command value adjustment unit 3121 is outside the dead zone Do due to the high traveling speed V, the forced control unit 4122 readjusts the command value Oa given to the steering actuator 3 to a difference operation value between the adjustment value and the width of the dead zone Do. At this time, the forced control unit 4122 supplies the width of the dead zone Do on the same side to the difference operation for the positive and negative of the adjustment value based on the angle follow-up control. On the other hand, in the stop control, for example, when the adjustment value Of the angle follow-up control by the command value adjustment unit 3121 is within the dead zone Do due to a decrease in the traveling speed V or the like, the forced control unit 4122 converts the command value Oa given to the steering actuator 3 to the fixed value Of. That is, the forcing control unit 4122 forces all the command values Oa in the dead zone Do among the adjustment values based on the angle follow-up control to the fixed value Of. By switching these readjustment processing and forced processing, the inside-outside abrupt change of the command value Oa given to the steering actuator 3 in the dead zone dθ is suppressed.

As shown in fig. 23, the forced control unit 4122 may convert the command value Oa in the dead zone Do to a fixed value Of if by fixing a predetermined control variable in the PID control in the command value adjustment unit 3121. Here, one of the control points P1a and P2a similar to the case of the third embodiment is selected for the variable fixed point in the PID control.

The forced control unit 4122 executes the release control in the same manner as in the third embodiment during the normal control period Δn in which the stop control off flag Foff is given from the control switching unit 100, and then executes the normal control.

The control switching flow in the steering control flow in the fourth embodiment is executed based on the first and third embodiments. On the other hand, the forced control flow in the steering control flow in the fourth embodiment is different from the third embodiment as shown in fig. 24.

In S3201 to S3203 of the forced control flow, in S4201 shifted by the affirmative determination in S3201 performed based on the third embodiment, the target angle adjustment unit 113 adjusts the target angle θt given to the angle follow-up control unit 4120 by performing the track follow-up control for causing the own state quantity Z to follow the target track Tz. However, in S4202 that follows, the forced control unit 4122 determines whether or not the command value Oa by the angle follow-up control corresponding to the adjustment angle in the command value adjustment unit 3121 is within the dead zone Do corresponding to the travel speed V in order to control the command value Oa, regardless of the adjustment angle in S4201.

In the case where a negative determination is made in S4201, the forced control flow moves to S4203. In S4203, the forcing control unit 4122 readjust the command value Oa adjusted to be outside the dead zone Do by the angle follow-up control of the command value adjustment unit 3121 to the difference value between the dead zone dθ and the steering actuator 3.

In the case where an affirmative determination is made in S4201, the forced control flow moves to S4204. In S4204, the forced control unit 4122 forcibly converts the command value Oa adjusted to the dead zone Do by the angle follow-up control Of the command value adjustment unit 3121 into a fixed value Of given to the steering actuator 3.

After executing either of S4203 and S4204, the forced control flow also moves to S3206 with reference to the third embodiment. As a result, when a negative determination is made, the flow returns to S4201. On the other hand, in the case where an affirmative determination is made, S3207 to S3209 are executed with reference to the third embodiment.

In the fourth embodiment described so far, S3202, S4201, S3207 correspond to the "track following control process", and S3201, S3203, S4202 to S4204, S3206, S3208, S3209 correspond to the "angle following control process".

(effects of action)

The operational effects of the fourth embodiment described above, which are different from those of the first embodiment, will be described below.

According to the fourth embodiment, the command value Oa is converted into the fixed value Of in the dead zone Do set for the stop control period Δs. Accordingly, the actual angle θr corresponding to the fixed value Of in the dead zone Do is given from the steering actuator 3 to the steering tire 20, and the variation Of the steering angle θ, which becomes the actual angle θr, can be restricted. Therefore, the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while being stopped can be suppressed as much as possible in accordance with the dead zone Do.

According to the fourth embodiment, in the dead zone Do set to a larger value range as the traveling speed V Of the vehicle 2 decreases in the stop control period Δs, the command value Oa is converted to the fixed value Of. Accordingly, the variation can be suppressed as the running speed V decreases, with respect to the steering angle θ which is the actual angle θr corresponding to the command value Oa which is more easily forced to the fixed value Of if as the running speed V decreases with the stop Of the vehicle 2. Therefore, the suppression effect corresponding to the dead zone Do can be exhibited against the sense of incongruity felt by the occupant due to the variation in the steering angle θ of the vehicle 2 while it is stopped.

(other embodiments)

The above description has been given of the embodiments, but the present disclosure is not limited to the embodiments and is applicable to various embodiments and combinations within a range not departing from the gist of the present disclosure.

In the modification, the dedicated computer constituting the steering control apparatus 1 may be at least one external center computer capable of communicating with the vehicle 2. In the modification, the dedicated computer constituting the steering control apparatus 1 may include at least one of a digital circuit and an analog circuit as the processor. Here, the digital circuit is at least one of ASIC (Application Specific Integrated Circuit: application specific integrated circuit), FPGA (Field Programmable Gate Array: field programmable gate array), SOC (System on a Chip), PGA (Programmable Gate Array: programmable gate array), and CPLD (Complex Programmable Logic Device: complex programmable logic device), for example. Further, such a digital circuit may be provided with a memory in which a program is stored.

In S101 of the control switching unit 100 according to the modification, the determination may be omitted with respect to one of the speed condition Cs1 and the steering condition Cs2, which is the start condition of the stop control period Δs. In S103 of the control switching unit 100 according to the modification, the determination may be omitted with respect to one or both of the speed condition Cr1, the static steering condition Cr2, and the track condition Cr3, which are the release conditions for the stop control period Δs.

In S207 of the forced control units 114 and 2114 according to the modification, instead of the release control, the target angle θt given to the angle follow-up control unit 120 may be directly controlled to the adjustment angle by the target angle adjustment unit 113. In this case, S209 by the forcing control units 114 and 2114 may be omitted. In S3208 of the forced control units 3122, 4122 according to the modification, the command value Oa given to the steering actuator 3 may be directly controlled to the adjustment value by the command value adjustment unit 3121 instead of the release control. In this case, S3209 by the forced control units 3122 and 4122 may be omitted.

In S2201 of the forced control unit 2114 according to the modification, instead of the dead zone dθ corresponding to the travel speed V, the dead zone dθ having a larger angle range may be set as the elapsed time from the start timing of the stop control period Δs increases. In S4202 of the forced control unit 4122 according to the modification, instead of the dead zone Do corresponding to the travel speed V, the dead zone Do having a larger angle range may be set as the elapsed time from the start timing of the stop control period Δs increases.

Claims

1. A steering control apparatus that controls steering of a vehicle based on a steering actuator, wherein the steering control apparatus includes:

a track following control unit that adjusts a target angle of a steering angle given to a tire of the vehicle by track following control that causes a self-state quantity including a position of the vehicle to follow a target track; and

an angle follow-up control unit that adjusts a command value that is given to the steering actuator and that corresponds to the actual angle by angle follow-up control that causes the actual angle of the steering angle to follow the target angle,

the track following control unit forces the target angle to a fixed angle during a stop control period accompanying a stop of the vehicle.

2. The steering control apparatus according to claim 1, wherein,

the track following control section maintains the target angle at the fixed angle throughout the stop control period.

3. The steering control apparatus according to claim 1, wherein,

the track following control section converts the target angle in a dead zone set for the stop control period into the fixed angle.

4. The steering control apparatus according to claim 3, wherein,

the dead zone is set to a larger angle range as the running speed of the vehicle decreases during the stop control.

5. The steering control apparatus according to any one of claims 1 to 4, wherein,

the track following control unit releases the stop control period in association with the static steering of the tire during the stop control period.

6. The steering control apparatus according to any one of claims 1 to 4, wherein,

the track following control unit releases the stop control period, assuming that the track is offset between the estimated track corresponding to the actual angle and the target track during the stop control period.

7. The steering control apparatus according to any one of claims 1 to 4, wherein,

the track following control unit gradually changes the target angle from the fixed angle toward an adjustment angle based on the track following control in response to the release during the stop control.

8. A steering control apparatus that controls steering of a vehicle based on a steering actuator, wherein the steering control apparatus includes:

9. The steering control device according to claim 8, wherein,

the angle follow-up control section maintains the command value at the fixed value throughout the stop control period.

10. The steering control device according to claim 8, wherein,

the angle follow-up control unit converts the command value in the dead zone set for the stop control period into the fixed value.

11. The steering control device according to claim 10, wherein,

the dead zone is set to a larger value range as the running speed of the vehicle decreases during the stop control.

12. The steering control apparatus according to any one of claims 8 to 11, wherein,

the angle follow-up control unit releases the stop control period in association with the static steering of the tire during the stop control period.

13. The steering control apparatus according to any one of claims 8 to 11, wherein,

the angle follow-up control unit releases the stop control period, assuming that a track shift between an estimated track corresponding to the actual angle and the target track is performed during the stop control period.

14. The steering control apparatus according to any one of claims 8 to 11, wherein,

the angle follow-up control unit gradually changes the command value from the fixed value to an adjustment value based on the angle follow-up control in association with the release of the stop control period.

15. A steering control method that controls steering of a vehicle based on a steering actuator, wherein the steering control method includes:

a track following control step of adjusting a target angle of a steering angle given to a tire of the vehicle by track following control for causing a self state quantity including a position of the vehicle to follow a target track; and

16. The steering control method according to claim 15, wherein,

the track following control step maintains the target angle at the fixed angle throughout the stop control period.

17. The steering control method according to claim 15, wherein,

the track following control step converts the target angle in the dead zone set during the stop control to the fixed angle.

18. The steering control method according to claim 17, wherein,

19. The steering control method according to any one of claims 15 to 18, wherein,

the track following control step releases the stop control period in association with the static steering of the tire during the stop control period.

20. The steering control method according to any one of claims 15 to 18, wherein,

the track following control step releases the stop control period, assuming that a track offset between the estimated track corresponding to the actual angle and the target track is present during the stop control period.

21. The steering control method according to any one of claims 15 to 18, wherein,

the track following control step gradually changes the target angle from the fixed angle toward an adjustment angle based on the track following control in association with the release during the stop control.

22. A steering control method that controls steering of a vehicle based on a steering actuator, wherein the steering control method includes:

23. The steering control method according to claim 22, wherein,

the angle follow-up control step maintains the command value at the fixed value throughout the stop control period.

24. The steering control method according to claim 22, wherein,

the angle follow-up control step converts the command value in the dead zone set for the stop control period into the fixed value.

25. The steering control method according to claim 24, wherein,

26. The steering control method according to any one of claims 22 to 25, wherein,

the angle follow-up control step releases the stop control period in association with the static steering of the tire during the stop control period.

27. The steering control method according to any one of claims 22 to 25, wherein,

the angle follow-up control step releases the stop control period, assuming that a track shift between the estimated track corresponding to the actual angle and the target track is performed during the stop control period.

28. The steering control method according to any one of claims 22 to 25, wherein,

the angle follow-up control step gradually changes the command value from the fixed value to an adjustment value based on the angle follow-up control in association with the release of the stop control period.

29. A storage device storing a steering control program containing a command to be executed by a processor in order to control steering of a vehicle based on a steering actuator, wherein,

the command includes:

the track following control step forces the target angle to be a fixed angle during a stop control period accompanying a stop of the vehicle.

30. A storage device storing a steering control program containing a command to be executed by a processor in order to control steering of a vehicle based on a steering actuator, wherein,

The command includes: